This invention relates to a bobbin doffing and donning apparatus applicable to spinning machines and, in particular, to bobbin holders employed in a bobbin doffing and donning apparatus for transferring bobbins between predetermined positions.
Generally, the doffing and donning apparatus, which may be stationary or movable along the side of the spinning machine, includes a doffing bar extending in parallel with the spinning machine and supporting a succession of bobbin holders thereon in equispaced relationship. Each bobbin holder comprises a hollow body or housing mounted on the doffing bar with a bobbin receiving opening vertically extending through the housing for receiving the bobbin, a stationary bobbin holding member disposed within the housing so as to oppose the bobbin receiving opening, and a movable bobbin holding member movable radially relative to the opening between a projected position and a retracted position. When fluid pressure is applied on the movable bobbin holding member, it is driven into the projected position and holds the bobbin in cooperation with the stationary bobbin holding member.
Such a bobbin holder is disclosed, for example, in Japanese published Utility Model Specification No. 53-12825, wherein a cover plate is attached through a flexible diaphragm to the base portion of the housing in fluid sealing relationship. In order to supply the fluid into each of the spaces between the cover plates and the respective diaphragms thereby to cause the corresponding movable bobbin holding members to be moved into their projected positions, a fluid hole opening into the corresponding space is provided in each cover plate and another fluid hole in fluid communication with such hole provided in the cover plate is also formed in the doffing bar. Moreover, a fluid pipe supplied with the fluid from a source of supply external to the doffing apparatus extends along the doffing bar and the fluid pipe is connected through connecting plugs to the fluid holes in the doffing bar. Thus, the pressurized fluid from the external source can be fed through the fluid pipe and the fluid holes provided in both the doffing bar and the cover plates into the spaces between the cover plates and the diaphragms, whereby the movable bobbin holding members are projected into their operative positions through the diaphragms by the pressurized fluid.
However, the doffing and donning apparatus employing these prior bobbin holders necessarily requires the forming of numerous sets of fluid holes in the doffing bar and the cover plates and to provide the doffing bar with numerous connecting plugs for the connection of the fluid pipe. This is disadvantageous in that additional time and labor is required to manufacture the doffing and donning apparatus. Also, in assembling the holders into the doffing and donning apparatus, each of the housings of the holders has to be accurately mounted on the doffing bar so as to permit each fluid hole in the cover plate to be in alignment with the corresponding fluid hole formed in the doffing bar. This assembling operation is apparently very troublesome.
Moreover, it has been proposed to form a doffing bar in the form of a duct to which a fluid pipe is connected through a single connecting plug to supply fluid into the duct. This arrangement can employ a simpler piping system than that disclosed in the above-discussed Japanese published Utility Model Specification No. 53-12825, since only a single connecting plug is required. However, since numerous fluid holes have to be formed in the duct at numerous positions corresponding to fluid holes provided in the respective cover plates of the holders, the aforementioned disadvantages of requiring the additional time and labor and the troublesome assembling operation remain. This arrangement also has disadvantages in requiring that the doffing bar be of a relatively large size and that there be a large capacity of a fluid supply source to be employed, because of the employment of the duct-like doffing bar. Furthermore, a wall of the duct to which each housing is attached by screws must be of a sufficient thickness so as not to allow the fluid present in the duct to leak out through the openings provided in the duct for the screws. This clearly results in a heavy doffing bar.
It is therefore a principal object of this invention to provide a bobbin holding device including at least one bobbin holder mounted on a doffing bar, which can remove all the disadvantages of the prior art.